1. Field of Invention
The invention relates generally to a valve assembly. More specifically, the invention relates to a backseat assembly for a gate valve assembly that is pivotable with respect to a stem of the gate valve assembly.
2. Description of Prior Art
Gate valves typically have a body with a cavity intersected by a flow passage. A gate moves in the cavity between a closed position, blocking flow through the flow passage and an open position that allows flow through the passage. A stem is usually included for moving the gate that engages the gate, and when rotated, causes the movement of the gate. The stem extends through a stem passage in the body of the gate valve. Stem seals seal between the stem and the stem passage, preventing leakage of pressure from the cavity.
Gate valves sometimes include a backseat feature for sealing between a valve stem and valve bonnet so that packing in the valve assembly can be changed. Backseats are typically made up of complimentary profiled surfaces in the stem and valve bonnet that when urged together isolate pressure communication along the stem. Backseats are generally energized by the pressure in the flow through the valve exerting a force on a bottom surface of the valve stem and urging together the profiled surfaces in the stem and bonnet.